Answer can be found in the vid I posted above, game is hardly any time consuming now.
It really depends on which activity are you doing. Sure, if you only do dailies, scenarios, etc, it doesn't take much time. If you want to cap your valor points, you'll have to put some time into the game, though.
If you're chasing Heroic raid kills, you'll have to devote time as well. That's the beauty of the game these days, you can devote as much time as you want (and your reward will probably be comparable to how much time you've spent).
It doesn't matter if you don't get to see an end boss, it tells you hey I need to put some effort into this game if I want to do it, and before I get to see the end boss I have to experience the other fights as well.
For some it does. It was kinda weird for some people to see Illidan on the cinematic in TBC and never get to see him while he was current content because of <insert whichever reason>.
If you don't have enough time well that is a different thing, but allow people that have or find time and put effort to feel awarded for it, don't just let everyone who can press Join LFR see and defeat the boss.
People that have time (and the will) can defeat Heroic bosses and get rewarded much more than someone seeing the content through LFR. And from time to time there're bosses that are exclusive to Heroic raiders (Algalon, Sinestra, and now Ra-den when 5.2 is released).
That's what in my opinion new WoW will never have and why old way of raiding will always be better than the current one, it simply does not feel rewarding enough for people that want to put effort and this has absolutely nothing to do with nostalgia because it's a fact, whoever raided whoever spent hours grinding/gearing after finishing what they started (eg Illidan) they could say I feel proud of myself and get a sense of accomplishment something people today will NEVER feel.
It's your opinion, so you can't make it a fact. I feel as proud of my Arthas kill as I do of my TBC/Wrath/MoP kills. It's just up to you to how much importance you wish to give to those events.
For me Arthas ranks higher than the others. Why? Because I've liked the Lich King character for a really long time and I feel his story (Arthas) was interesting to me.
Anyone saying FOR A FACT that any stage of this game was the best, is a person unable to grasp the simple concept of "subjectivity". What one considers the peak of existence for this game, others didn't even bother coming back to beyond reaching max level.
True. As much as I love those evenings in BRD with my friends, I wouldn't have the time for it today. Time changes.